<p>Voici Microsoft’s statement regarding Universal Groups. Especially the bolded part pertains to you:</p>
<blockquote></blockquote>
<p>Universal groups can be used anywhere in le même Windows<br>
forest. They are only available in a Native-mode enterprise. Universal<br>
groups may be an easier approach for some administrators because there<br>
are no intrinsic limitations on their use. Users can be directly<br>
assigned to Universal groups, they can be nested, and they can be used<br>
directly with access-control lists to denote access permissions in any<br>
domain in the enterprise.</p>
<p>Universal groups are stored in the global catalog (GC); this means<br>
that all changes made to these groups engender replication to all<br>
global catalog servers in the entire enterprise. <strong>Changes to universal<br>
groups must therefore be made only after a careful examination of the<br>
benefits of universal groups as compared to the cost of the increased<br>
global catalog replication load. If an organization has but a single,<br>
well-connected LAN, no performance degradation should be experienced,<br>
while widely dispersed sites might experience a significant impact.<br>
Typically, organizations using WANs should use Universal groups only<br>
for relatively static groups in which memberships change rarely.</strong></p>
<p>The performance impact should be rather minimal in a well-connected environment where everyone has access to global catalogs.</p>
<p>The performance impact will be increased time to log in and increased time to evaluate ACLs on resources <strong>if</strong> a global catalog cannot be reached, or if your Sites & Subnets are misconfigured so that you find yourself communicating with global catalog servers outside of your own site. Also, there will be increased global catalog replication load.</p>
<p><strong>Cependant,</strong> I’m obliged to once again inform you that what you’re doing is against commonly-accepted bonne pratiques.</p>
<p>This part of what you said: <em>“… and my tool will watch for the right security by itself.”</em> That also scares me.</p>
<p>So I’m on the side of your IT consultants and Je pense they are doing their jobs by trying to persuade you to follow commonly-accepted bonne pratiques in terms of AD design.</p>
<p>But there’s the answer to your question regardless.</p>